Wednesday 11 November 2009 04.16 EST
First published on Wednesday 11 November 2009 04.16 EST

As his publisher Jane Johnson, an author herself, puts the finishing touches to a roast chicken in the kitchen, Kim Stanley Robinson – Stan – tries to explain his new theory of time travel, worked out for his latest novel, Galileo's Dream.

"Time is strangely braided. I see Jane today, when I haven't seen her since 2004, and we first met in 1991. I can remember that meeting – it seems like just yesterday, but also like several million years ago; it has both elements," says Robinson, a warm, articulate Californian who, despite his jetlag, peppers his conversation with references to science and scientists, philosophers, historians, novelists – it's hard to keep up. "So I wanted to talk about that and then the backwards-ness, the third strand. Walter Benjamin talked about it – you go forwards in time but we're always looking backwards in a rear view mirror. That struck me as interesting."

So in Galileo's Dream – on the one hand a scrupulously accurate, joyfully affectionate portrait of the life of the first modern scientist, Galileo Galilei; on the other a wild leap through the solar system to the moons of Jupiter and a future civilisation – Robinson set out to pin down time travel.

What he came up with was three different temporal dimensions – the first moving very fast, at the speed of light, the second very slow and "vibrating slowly back and forth, as if the universe itself were a single string or bubble", the third – antichronos – in reverse. We experience them as one, creating a three-way interference pattern, which accounts for sensations such as foresight, déjà vu, nostalgia and precognition. The compound nature of time, Robinson writes, "creates our perception of both transience and permanence, of being and becoming". He's shown the novel to people who are "much more serious about the time travel stuff" and they're "having a blast". "They immediately map my three strands of time onto their system. They think I've partially discovered the real thing," he says gleefully.

His time travel theory is a remarkably plausible one, but then it would be. Robinson, winner of almost every science fiction prize going, and one of the genre's modern greats, describes himself as a realist and as a conservative in his literary aesthetics, despite his leftwing politics. For anyone who's read his Mars trilogy – the books which made his name – this is immediately obvious: the meticulous realism of this world, the geography, the science, the psychology, the terraforming, the politics, all have their roots in the feasible, despite their far-flung setting.

Galileo's Dream is the first time the 57-year-old has tackled time travel, and also the first time aliens have appeared in his books. (They manifest as a moon-sized consciousness, unutterably other: "Essentially I sort of believe Stanislaw Lem. If we did run into an alien intelligence we'd be reduced to doing what Galileo suggests [in the novel] – drawing Pythagoras's theorem and seeing if they're in the same physical cosmos as us. And that's about all you could say to an alien," says Robinson. "So these aliens which proliferate in science fiction – well, I don't think that's the way it's going to be.") It's also the first time he's focused on a real historical figure.

"This book has sort of released me," he says with a grin, settling into the couch in Johnson's Putney flat (he's in the UK on a flying visit from his home in California, on the way to a Galileo convention in Italy). The germ of it began when he was researching his alternate history, The Years of Rice and Salt – in which the Plague has wiped out 95% of the population of Europe, leaving the East in the ascendant – and needed to come up with an alternative scientific revolution. Studying our own, he found Galileo "right in the middle of it". "I put that aside but thought 'there's an interesting story'," says Robinson. "He seemed like such a confident guy, you might even say a brash guy – you could put him in any situation."

As he continued to research Galileo – and there was a lot to read, as his life is very well documented – Robinson began to fall for the man himself, for his arrogance, his jollity, his recklessness and his "tremendous human story". The result, all science fiction aside, is a wonderfully warm, accurate portrayal of the man. "I didn't want to mess with that. His life is too interesting to disturb," says Robinson, an English major who is married to a chemist, and fascinated with the "totally rational, but actually boilingly emotional personality" of the "hardcore scientist".

So Galileo makes his telescope. He sees the Seven Sisters constellation, surrounded by "thickets of lesser stars, granulated almost to white dust in places ... No one else in the history of the world had ever seen these stars, until this very night, this very moment". He discovers Jupiter's four moons. He studies acceleration and motion. He observes sunspots. He frequently, frequently rings "like a struck bell" as his genius strikes: "Here it was, the truth of the situation – the cosmos revealed in a single stroke as being one way rather than another. The Earth was spinning under his feet, also rolling around the sun ... Again he rang like a bell. His flesh buzzed like struck bronze, his hair stood on end. How things worked; it had to be; and he rang." He stamps on the ground after he is tried by the Inquisition for supporting Copernicanism: "'It still moves!' he said. 'Eppur si muove!'"

But Robinson is, of course, a science fiction writer, and so there is a whole other side to Galileo's Dream (as hinted by the title's allusion to Bottom's dream: "I have had a most rare vision. I have had a dream past the wit of man to say what dream it was"). And as he started to sketch out his idea of a troubled far future civilisation on the moons of Jupiter, to which Galileo is transported to advise as the people make their first alien contact, he began to spot "a lot of strange things". "I kept running into things he said, or Giordano Bruno said, which all seemed to support my science fiction ideas. For them to say Jupiter or the sun was alive was perfect. Especially the sun – Galileo is quite specific about that."

He quotes Galileo writing to a correspondent named Dini: "I have already discovered a constant generation on the solar body of dark substances ... and I have discussed how they could perhaps be regarded as part of the nourishment (or perhaps its excrements) that some ancient philosophers thought the Sun needed for its sustenance". "I discovered that later on as a kind of mind-boggling confirmation," Robinson says. "I saw that sentence and I did, I rang like a bell."

He was concerned about putting words into Galileo's mouth – "I always felt nervous about it. In fact I held that opinion until I began this that yes, it is morally objectionable" – but his far future setting assuaged his conscience. "I'm not trying to imagine what Galileo said to the Pope – I'm adding extra things like if Galileo had a dream like this, he would say things like that. And so it was complicated but it was a lot of fun."

He's not even nervous about the reception he'll receive at the Galileo convention (to which, he shows me, he is taking a small doll of the scientist). "Nobody can fault the Galileo scholarship. I haven't done a superficial biography," he says. "I think you can read the novel and get a very solid sense of what happened to Galileo – everything I added can be very clearly seen."

Part of it is because he feels his bombastic hero "would probably think, OK – 400 years later, even 3,000 years later, I'm still famous" (his Galileo, enchantingly, is delighted to discover that Jupiter's moons are now named for him, having obsequiously named them after his patron). Part of it was down to his increasing affection for his sometimes curmudgeonly subject: "the falling-in-love-with-Galileo syndrome meant that I began to get a lot of confidence that in any situation I could imagine what he would say. There was this recklessness, or this arrogance. He got in trouble for real obvious reasons, he made enemies of many different kinds. He was just kind of heedless. And in a way he was the model of the early scientist, so absorbed in his own concerns he was oblivious to the larger political considerations. Which was very dangerous in his time, and has gotten less physically dangerous, but is always a mistake."

In Galileo's time, science was clashing with religion; today, Robinson believes, we're living in a "Galilean moment" again, in which climate change means science has become politicised. This time, though, the clash is with capitalism. "There are cultural forces in our society which say, you can save the world or else you can make a profit, and they'll say sorry, we have to make a profit. So we have a strange religion now." As his global-warming-themed trilogy, which ends with 2007's Sixty Days and Counting, shows, a major theme for Robinson is ecological sustainability, and he stresses today his belief that "the climate crisis is an emergency".

Growing up in 50s and 60s California, he saw the agricultural landscape he knew change "absolutely" over a period of about 10 years – this is partly the reason he began reading, and then writing, science fiction, because it "described what I experienced". He'd originally been a reader of historical fiction, running into science fiction at college when his adviser sent him off to read Philip K Dick. He published his first short story aged 20, ended up writing his 1982 PhD thesis on Dick, and is now the author of 16 novels and numerous short stories.

Today, he says, "we're all in a science fiction novel". "If you go home, turn on the laptop, the TV – almost anything could be reported. The world has become a science fiction novel, everything's changing so quickly. Science fiction turns out to be the realism of our time, which is very satisfying."

But this rapid change, in turn, leads to another sort of crisis. "Depending what we do in next 20 years, it's very hard to be plausible, to say this is what's going to happen. At that point you can't write science fiction, [so] the genre is in a little bit of a crisis, and all the young people are reading fantasy." Robinson himself, however, presses on undaunted. He's considering future novels set around Saturn or Mercury; he's looking into a book about Herman Melville, who "after his career as a novelist crashed had another career as a customs inspector"; he's keen to put what he learnt from Galileo – the work ethic, "the tenacity of the man", into practice.

But he worries about "the crisis for this tiny genre", recently launching an impassioned defence of science fiction in the New Scientist, where he accused the Man Booker judges of neglecting what he called "the best British literature of our time". "It's a different situation than it was when I began, the relation between world and genre. Back then you could read science fiction and get a sense of what the world was going to be – now, I don't think you can be prophets in the same way," he says. "If the world is a science fiction novel then what do you read? What can the literature do for you?"